As a jet engine of a fuselage which can fly faster than the velocity of sound, a turbo jet engine (containing a turbo fan engine), a ram jet engine and a scram jet engine are known. These types of jet engines take in air and operate. Especially, in the ram jet engine and the scram jet engine, the speed of the taken-in air strongly depends on the flight speed.
FIG. 1A and FIG. 1B are a sectional view schematically showing the configuration of the jet engine. Here, FIG. 1A shows a state when the flight speed is slow, and FIG. 1B shows a state when the flight speed is fast. The jet engine 102 is provided with a fuselage 110 and a cowl 140 provided below the fuselage 110 to form a space 150 through which gas can flow. A font lower part of the fuselage 110 and a front part of the cowl 140 configure an inlet 111 which introduces air into the space 150. A middle lower part of the fuselage 110 and a middle part of the cowl 140 configure a combustor 112 to mix and combust fuel and air. A rear lower part of the fuselage 110 and a rear part of the cowl 140 configure a nozzle 113 which expands and emits a combustion gas. The combustor 112 contains a fuel injector 120 and a flame stabilizer 121. The fuel injector 120 is provided for a part corresponding to the combustor 112 of the lower part of the fuselage 110. The fuel injector 120 injects fuel G for the space 150. The flame stabilizer 121 is provided in a rear part from the fuel injector 120 in a part corresponding to the combustor 112 of the lower part of the fuselage 110. The flame stabilizer 121 maintains a flame F for the combustion by using the fuel G from the fuel injector 120. The jet engine 102 mixes the air taken in from the inlet 111 and the fuel G injected from the fuel injector 120 in the combustor 112 and combusts the mixture. The combustion gas is expanded in the nozzle 113 and is sent out to the rear direction of the fuselage 110. The flame F of the flame stabilizer 121 is used for the maintenance of the combustion.
In the front of the flame stabilizer 121 of the combustor 112, a high-pressure region HP is formed. The extension of the high-pressure region HP is mainly determined based on the balance of a combustion pressure of the combustion in the combustor 112 and a dynamic pressure of the air taken-in from the inlet 111. In case (FIG. 1B) that the flight speed is fast (mainly, in a cruising stage of the flying object), and the dynamic pressure of air is high, the high-pressure region HP becomes narrow. On the other hand, in case that the flight speed is slow (in an acceleration stage of the flying object) and the dynamic pressure of the air is low, the high-pressure region HP gets widely (FIG. 1A).
As a related technique, a variable type flame holder of a jet engine is disclosed in Japanese Laid Open Patent Application (JP H09-250395A). This variable type flame holder is provided with a plurality of variable wings installed in an after-burner section of the jet engine and a fuel injector to make fuel inject in the rear part of the variable wing. This variable type flame holder changes an angle of attack of the variable wing to form an optimal dead water region in the rear part of the variable wings and carries out the flame stabilization in the dead water region. This variable type flame holder transforms the shape of the flame holder with a mechanical mechanism.